Finch (6)
I believe the answer is:
linnet
'finch' is the definition.
(I know that linnet is a type of finch)
This is all the clue.
(Other definitions for linnet that I've seen before include "Type of finch" , "Songbird in Lent" , "Finch so named because it feeds on flax" , "Yeats's song-bird" , "Songbird (to 6 18)" .)